从csv文件创建字典？

Question

我正在尝试从csv文件创建一个字典。 csv文件的第一列包含唯一键，第二列包含值。 csv文件的每一行代表字典中唯一的键值对。我试图使用csv.DictReader和csv.DictWriter类，但我只能弄清楚如何为每一行生成一个新的字典。我想要一本字典。这是我尝试使用的代码：

import csv

with open('coors.csv', mode='r') as infile:
    reader = csv.reader(infile)
    with open('coors_new.csv', mode='w') as outfile:
    writer = csv.writer(outfile)
    for rows in reader:
        k = rows[0]
        v = rows[1]
        mydict = {k:v for k, v in rows}
    print(mydict)

当我运行上面的代码时，我得到了一个ValueError: too many values to unpack (expected 2)。如何从csv文件创建一个字典？谢谢。

Answer 1

我相信你要找的语法如下：

with open('coors.csv', mode='r') as infile:
    reader = csv.reader(infile)
    with open('coors_new.csv', mode='w') as outfile:
        writer = csv.writer(outfile)
        mydict = {rows[0]:rows[1] for rows in reader}

或者，对于python <= 2.7.1，您需要：

mydict = dict((rows[0],rows[1]) for rows in reader)

Answer 2

单线解决方案

import pandas as pd

dict = {row[0] : row[1] for _, row in pd.read_csv("file.csv").iterrows()}

Answer 3

通过调用open然后csv.DictReader打开文件。

input_file = csv.DictReader(open("coors.csv"))

您可以通过遍历input_file来迭代csv文件dict reader对象的行。

for row in input_file:
    print row

或仅访问第一行

dictobj = csv.DictReader(open('coors.csv')).next() 

Answer 4

import csv
reader = csv.reader(open('filename.csv', 'r'))
d = {}
for row in reader:
   k, v = row
   d[k] = v

Answer 5

你必须将csv.reader转换为dict：

~ >> cat > 1.csv
key1, value1
key2, value2
key2, value22
key3, value3

~ >> cat > d.py
import csv
with open('1.csv') as f:
    d = dict(filter(None, csv.reader(f)))

print(d)

~ >> python d.py
{'key3': ' value3', 'key2': ' value22', 'key1': ' value1'}

Answer 6

这不是优雅，而是使用熊猫的一线解决方案。

import pandas as pd
pd.read_csv('coors.csv', header=None, index_col=0, squeeze=True).to_dict()

如果要为索引指定dtype（如果因使用bug而使用index_col参数，则无法在read_csv中指定）：

import pandas as pd
pd.read_csv('coors.csv', header=None, dtype={0: str}).set_index(0).squeeze().to_dict()

Answer 7

你也可以使用numpy。

from numpy import loadtxt
key_value = loadtxt("filename.csv", delimiter=",")
mydict = { k:v for k,v in key_value }

Answer 8

我建议添加if rows，以防文件末尾有空行

import csv
with open('coors.csv', mode='r') as infile:
    reader = csv.reader(infile)
    with open('coors_new.csv', mode='w') as outfile:
        writer = csv.writer(outfile)
        mydict = dict(row[:2] for row in reader if row)

Answer 9

如果你可以使用numpy包，那么你可以执行以下操作：

import numpy as np

lines = np.genfromtxt("coors.csv", delimiter=",", dtype=None)
my_dict = dict()
for i in range(len(lines)):
   my_dict[lines[i][0]] = lines[i][1]

Answer 10

你可以使用它，这很酷：

import dataconverters.commas as commas
filename = 'test.csv'
with open(filename) as f:
      records, metadata = commas.parse(f)
      for row in records:
            print 'this is row in dictionary:'+rowenter code here